/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 刘柄华
 * Date: 2022-06-07
 * Time: 21:23
 */

// 树的子结构
// 输入两棵二叉树A，B，判断B是不是A的子结构。（我们约定空树不是任意一个树的子结构）
public class TestDemo01 {
    public boolean HasSubtree(TreeNode root1, TreeNode root2) {
        if (root2 == null || root1 == null) return false;
        boolean result = false;
        if (root1.val == root2.val) {
            // 注意这里不可以直接return !!!
            result = isSameChild(root1, root2);
        }
        if (result != true) {
            return HasSubtree(root1.left, root2) || HasSubtree(root1.right, root2);
        }

        return result;

    }

    public boolean isSameChild(TreeNode root1, TreeNode root2) {
        if (root2 == null) return true;
        if (root1 == null) return false;
        if (root1.val != root2.val) return false;
        return isSameChild(root1.left, root2.left) && isSameChild(root1.right, root2.right);
    }
}

class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }
}
